Spandau's last prisoner (4)
I believe the answer is:
'spandau's last prisoner' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for hess that I've seen before include "Cite as evidence" , "Famous pianist" , "Pianist Myra, Nazi Rudolf ---" , "leading Nazi" , "Rudolf ..., Nazi leader imprisoned at Spandau" .)